Thread rolling apparatus



p 1934- c. FASSINGER THREAD ROLLING. APPARATUS Filed Sept. 7, 1932 2SheetsSheet 2 l/l/l/ l/l llll l INVENTOR [mi V thr Patented Sept. 11,1934 UNITED STATES,

1'- OFFICE 3 Claims.

My invention relates to thread-rolling apparatusand a method of rollingthreads, particularly in the threading of bolts, screws, spikes and thelike.

In the threading of blanks, it has been common practice to so roll orforge the shank of a blank that the over-all diameter of the threadedportion thereof will be somewhat greater than the diameter of theoriginal blank, owing to the fact that the threads are produced bypressing the teeth of the dies into the blank 2. distance less than thedepth of the thread to be produced, the metal of the blank beingdisplaced and caused to swell out into the spaces between the teeth toform the tops of the threads. The over-all diameter of the finishedarticle is therefore somewhat greater than the original diameter of thebla One object of my invention is to so thread a blank that there willbeno substantial displacement of the metal in a radially outwarddirection, and to produce threads which will be quite dense, and freefrom ruptures through excessive displacement of the metal containedwithin the ead. Another object of my invention is to provide means forrolling threads by commencing at a point adjacent to the head of theblank and progressing toward the point or inner end thereof, instead ofapplying the threading teeth to the blank throughout substantially itsentire length at the beginning of the thread-forming operation.

Another object of my invention is to provide means for operatingthreading dies in such manner that danger of the blank slipping wheninitially engaged by the dies is minimized.

Still another object of my invention is to simplify and improvegenerally the methods of and apparatus for rolling threads.

One mannerin which my invention may be practiced is shown in theaccompanying drawings, wherein Figure 1 is a plan view of a threadingmachine; Fig. 2 is a side elevational view thereof; Fig. 3 is a crosssectional view, on an enlarged scale; Fig. 4 is a sectional view. of aportion of the apparatus of Fig. 3, on a still further enlarged scale;Fig. 5 is a sectional plan view of the structure of Fig. 4; Fig. 6 is aview similar to Fig. 4, but showing a completely threaded spike inposition between the dies;

Fig. 7 is a side elevational view showing one of the dies, and apartially rolled spike therein, and Fig. 8 is a plan view showing thespike beporting frame or base tween the dies at a Fig. 7.

The apparatus is shown as mounted on a sup- 10 wherein a shaft 11 isjournalled, the shaft being driven from any suitable source of power.The shaft 11 carries a pair of eccentrics 12 and 13, and a cam disc 14.

In the forward part of the frame 10 slideways 15 and 16 are provided,these slide-ways having suitable steel liner plates 17 and 18. Theslideway 15 is stationary while the slide-way 16 is periodically givensome lateral movement by means of hell cranks 19 that have their innerends pivotally connected to the slide-way 16 and their outer endsconnected to a pull rod 20,

partially rolled stage, as in the intermediate portions of the bellcranks pivotally connected to the frame 10. By this, the slideway 16 hasa lateral movement towards slide 15 at the beginning of each stroke, orcycle of the crankshaft, and also, a lateral movement away from slide 15at the end of each stroke or cycle of the crankshaft, so as tofacilitate engagement of the blanks and release thereof by the dies.

Dies 21 and 22 are removably supported on slides 23 and 24 respectively,in any suitable manner, as by clamping brackets 25, the slides 23 and 24being held in position on their slideways by brackets or clamping yokes26 and 27 respectively. The slides 23 and 24, of course, have slidingmovement on the slide-ways 15 and 16 as hereinafterdescribed, to effectrolling of threads on blanks.

The slides 23 and 24 are operated by eccentric rods 28 and 29,respectively, that are in turn connected to the eccentrics 12 and 13, sothat during rotation of the shaft 11'. the slides 23 and 24, and thedies carried thereby, will be simultaneously reciprocated in oppositedirections.

The cam disc 14'is of such contour that when the die 21 is in itsforemost position and the die 22 at its rearmost position, as shown inFig. 1, the rod 20 will be thrust forward to rock the cranks 19 incounter-clockwise directions to thrust the slide-way 16 toward theslide-way 15, thus gripping the blank 31 between the die blocks 21 and22, so that there will be no slipping of the blank about its axis at thebeginning of the rolling operation.

At the instant the blank is gripped, as aboveexplained, the eccentrics12 and 13 reach such positions that the die block 21 begins to movebackwardly, and the die 22 forwardly, and such movements are continueduntil the thread has been rolled on the blank 31. At the completion ofthe rolling operation, and preliminary to return movements of the dies,the raised surface of the cam disc 14 has passed out of engagement withthe roller 33, whereupon the rod 20 is retracted by pressure of a spring34 that operates against a nut 35 on the rod and a fixed stop shoulder36 that is secured to the base of the machine, and which serves also asa guide for the rod 20. The bell cranks 19 will thereby be swung in aclockwise direction, shifting the slide-way 16 laterally from theslideway 15. The dies are then returned by the eccentrics 12 and 13 tothe positions shown in Fig. 1.

Another important feature of my invention resides in the form of thedies 21 and 22, which is shown more clearly in Fig. 7. These die blocksare complementally formed, and have their thread-forming teeth formed insomewhat the usual manner, except at the entrance of the dies, theirtoothed portions are in effect tapered. through the fact that the teethare inclined or lie in diagonal lines, and. are so positioned that onlythe upper portion of the blank is initially engaged by the teeth, theteeth being brought progressively into engagement with the shank as therolling progresses.

The dies, during the rolling operation, are held so closely togetherthat the teeth will penetrate full depth into the blank, so that littleor none of the metal is extruded radially outward between thethread-rolling teeth. The metal displaced by the threading teeth iscaused to flow longitudinally of the blank and causes elongationthereof. If desired, the dies can be brought so closely together thatthe over-all diameter of the threaded blank will be even less than theoriginal diameter of the blank.

The operation described produces a threaded article wherein the metalforming the teeth has not been excessively distorted, and in fact may beconsiderably compressed to make for greater density and strength, andwithout minute ruptures that would weaken the teeth.

The blanks may be rolled either hot or cold, and the invention is ofparticular advantage in the rolling of railroad tie spikes and the like,where a considerable area of the spike is unthreaded at points betweenthe successive thread turns.

While the thread-forming elements of the dies are herein referred oasteeth, it will be seen that because they are of a form to producethreaded spikes of wide pitch, the teeth are in efiect wide-faced ribs,between which are groove like spaces having approximately the crosssectional form of the completed thread.

I claim as my invention:-

. 1. Thread-rolling apparatus comprising a pair of spaced diespositioned to receive a blank, each die being provided with a full-sizethread-forming tooth extending diagonally downwardly and rearwardly froma point adjacent to the upper forward corner thereof, to a pointadjacent to the lowermost edge of the die, means for moving the diestoward one another a distance sufiicient to initially compress the blankbetween the said teeth to the depth of the teeth, previous tothread-rolling movement of the dies, means for maintaining this relativelateral position of the dies during the rolling operation, and means op-,erating in timed relation to the first-named movement for moving thedies to effect rolling movement of the blank between the same.

2. Thread-rolling apparatus comprising a pair of laterally-spaced dieblocks, dies carried thereby in position to engage a blank at oppositesides thereof, eccentric mechanism for reciprocating said die blocks toeffect rolling of blanks between the dies, a bell crank device mountedat its mid point on a fixed pivot and connected at one end to one of thedie blocks, a rod having connection with the other end of the bellcrank, and a cam operating to shift said. rod in timed relation tomovement of the eccentric mechanism, the said cam having a raisedportion operating to rock the bell crank and bring said one die blocktoward the other, preliminary to the commencement of the rollingoperation, the said raised portion being of such length as to maintainthe spaced relation between th die blocks during blank-rolling movementthereof.

3. Thread-rolling apparatus comprising a pair of spaced dies positionedto receive a blank, each die being provided with a full-sizethread-forming tooth extending diagonally downwardly and rearwardly froma point adjacent to the upper forward corner thereof, to a pointadjacent to the lowermost edge of the die, and withsuccessively-arranged teeth disposed in parallelism with the first-namedtooth, means for moving the dies toward one another a distancesufficient to initially compress the blank between the said full-sizeteeth to the depth of said teeth, previous to thread-rolling movement ofthe dies, means for maintaining this relative lateral position of thedies during the rolling operation, and means operating in timed relationto the firstnamed movement for moving the dies to effect rollingmovement of the blank between the same.

- CHARLES FASSINGER.

